Drainage systems or roof drains are employed on most buildings to assist in controlling the flow of water running off from the roofs of buildings during rain storms, snow storms and the like. Although such drainage systems or roof drain assemblies have long existed and have been constructed in a wide and diverse manner, certain conditions have recently arisen that have endangered the safety of low sloped or flat roofs which do not have perimeter gutters or eaves which allow the water to flow off automatically.
In most constructions, buildings are formed with sloping or pitched roofs which allow rain water or water from melting snow and ice to flow off of the roof automatically due to the pitch angle. In most locations, perimeter gutters are employed in order to catch the water run-off and control the flow of the water to desired locations. However, in buildings or structures wherein a flat or low sloped roof is employed, the drainage of rain water or snow therefrom becomes a more severe and difficult problem.
In many buildings, a flat or low sloped roof is employed and has a peripherally surrounding parapet or abutment preventing the rain water from automatically flowing off of the roof. Although these roofs typically have an inward draining slope feeding into a central roof drain, the conventional roof drains commonly found on most of these roofs suffer from severe clogging problems, which prevent satisfactory drainage. Due to heavier than normal snowfall as well as unusually cold winters, snow and ice buildup has combined with debris, such as leaves, twigs, branches, etc. to cause the drain to clog. As a result, water often builds up on flat roofs which reduces the normal safe weight carry capacity originally designed into the roof structure. In addition, water seepage through the roof often occurs, causing damage to interior structures.
This problem of clogging roof drains in combination with heavier than normal snowfall during the winter months has caused several buildings throughout the country to experience actual collapse of the roof structure. In many jurisdictions throughout the United States, building codes have been changed to require parapets on flat roof buildings to be breached, in order to prevent roof flooding and allow water buildup to escape from the roof surface, as a safeguard against the collapse of the roof due to flooding.
In order to address these problems, many jurisdictions now require that new flat or low sloped roof constructions must incorporate a structure which will cause any water to flow in a single direction towards a roof drain, whether the drain employed constitutes perimeter gutters, spill-overs, or interior roof drains. Typically, these new building codes are not limited to only new structures but also apply to any existing structure which is being re-roofed or upgraded. Although these new requirements address this problem area, the conventional roof drains often become clogged with debris, ice, or snow, thereby preventing effective water flow control.
Another problem that repeatedly occurs in both existing flat and low pitched roofs which are being re-roofed or upgraded, as well as in such new roof constructions, is the incorporation of heavy insulation to reduce heat loss through the roof. Although heavy insulation may be desirable for heat retention within the building, the reduction of heat escaping through the roof reduces the rate of melting of the snow or ice existing on the roof. As a result, heavier accumulations of snow and ice occur on the roof, imposing a heavier load on the structure than was originally anticipated. In addition, by having an increased buildup of snow and ice on the roof, the normal drainage system installed on the roof can be overloaded or clogged, further compounding the build-up of an excessive weight on the roof structure, as well as the buildup of excess water.
These problems are further compounded with rapid changes in winter temperatures, where snow and ice build-up continues from earlier accumulations or for substantially longer periods of time than were originally contemplated. As a result, additional snow fall or heavy rain causes further clogging and the overloaded clogged drains are rendered effectively useless. As a result, the roof structure is exposed to an ever-increasing weight load as well as water damage due to seepage. Due to problems of this nature, it has been documented that roofs have collapsed with heavy rainfall or snowfall when the built-in structural maximum load design factors have been exceeded.
A further problem that has occurred due to these difficulties is found with cap flashings which peripherally surround abutting items such as sky lights, walls, vent stacks and equipment placed on the roof. Although cap flashings are designed to be sufficient to accommodate normal levels of snow and water accumulations on roofs, difficulty in removing water has caused the normal level to be exceeded. As a result, equipment and interior areas are being subjected to water exposure where none was anticipated. This not only affects the safety of the roof and the equipment's longevity, but also causes water to enter under the flashings and create interior wall damage or interior flooding.
Another problem that has plagued prior art drainage devices in general and roof drains in particular is the inability of the roof drain construction to satisfactorily deal with accumulation of debris frequently found on roofs. As discussed above, although snow and ice accumulation represents a substantial problem against which prior art roof drain structures have attempted to deal, a substantially greater problem that occurs is clogging of the roof drain grating or strainer by debris, such as leaves, twigs, branches, etc.
In most buildings, roof maintenance is minimal if existent at all. Consequently, buildup of debris around the roof drain usually goes unnoticed for long periods of time, allowing debris to continuously build until the entire roof drain grating or strainer has been virtually surrounded and realistically closed by an accumulation of such debris. This debris accumulation further compounds and exasperates the problems caused by snow and ice buildups, preventing the normal passage of water run-off to be achieved and allowing excessive weight loads and water levels to buildup on the roof surface.
Although many prior art systems have been developed in an attempt to overcome these prior art difficulties, prior art systems have been incapable of satisfactorily eliminating the hazards resulting from debris, snow, and ice buildup on the roof. Typically, drains or sumps with different sized and shaped domes or strainers have been employed using a plurality of alternate constructions and slot arrangements in an attempt to satisfy the need for adequate drainage. In spite of this extensive effort, the problems have not been overcome.
One method which has been employed in some constructions is the use of dual drains installed at different elevations in order to have a secondary drainage system which will function if the primary drainage system, at the lowest level, fails to operate properly. Although the employment of dual drains can be successful in overcoming some of the prior art difficulties presently occurring in flat and low sloped roofs, this approach is extremely expensive and is not a universal solution for all presently existing problems. In addition, since the use of dual drainage systems at alternate height levels is extremely expensive, the approach is often precluded due to its additional cost.
Therefore, it is a principal object of the present invention to provide a roof drain assembly for use on fiat roofs and low slope roofs which is capable of virtually eliminating unwanted water accumulation due to clogging or backup from debris, ice and snow.
Another object of the present invention is to provide a roof drainage assembly having the characteristic features described above which is capable of being easily installed on virtually all flat and low sloped roofs with complete assurance that unwanted clogging or water accumulation will be eliminated.
Another object of the present invention is to provide a roof drain assembly having the characteristic features described above which is easily installed in both new and existing roof constructions with complete compatibility.
Another object of the present invention is to provide a roof drain assembly having the characteristic features described above which is highly effective in eliminating excess water accumulation which is also economical to employ.
Other and more specific objects will in part be obvious and will in part appear hereinafter.